Alert archive / Idaho / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 15, NWS Pocatello, ID

August 21, 20214 counties in Idaho

NWS Pocatello, ID issued this severe thunderstorm warning at Aug 21, 2021, 3:05 PM MDT for 4 counties in Idaho. It was in force for 29 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 21, 2021, 3:05 PM MDT (21:05 UTC)
Expired
Aug 21, 2021, 3:34 PM MDT
In force
29 min
Issued by
NWS Pocatello, ID
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Bannock County, ID, Bear Lake County, ID, Caribou County, ID, Franklin County, ID

The radar

The Pocatello radar (KSFX), 117 km from the middle of the area, began a volume at 21:09 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 21, 3:10 PM MDTTSTM WND GST 466 Nw Mink Creek, IDMEASURED AT TREASURETON SUMMIT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 9.1 hours before the alert went out and 176 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Salt Lake City I, UT at 12:00Z on 2021-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 77 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Salt Lake City I, UT at 12:00Z on 2021-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 239 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
77 J/kg
Mixed-layer CIN
-271 J/kg
Mixed-layer LCL
2167 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
239 m²/s²
0-3 km storm-relative helicity
260 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

805 
WUUS55 KPIH 212105
SVRPIH
IDC005-007-029-041-212145-
/O.NEW.KPIH.SV.W.0015.210821T2105Z-210821T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Pocatello ID
305 PM MDT Sat Aug 21 2021

The National Weather Service in Pocatello has issued a

* Severe Thunderstorm Warning for...
  South central Caribou County in southeastern Idaho...
  Southeastern Bannock County in southeastern Idaho...
  Northeastern Franklin County in southeastern Idaho...
  Northwestern Bear Lake County in southeastern Idaho...

* Until 345 PM MDT.

* At 304 PM MDT, a severe thunderstorm was located over Oneida
  Narrows Reservoir, or 13 miles east of Swanlake, moving northeast
  at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Georgetown, Thatcher, Oneida Narrows Reservoir and Emmigrant
  Summit.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4219 11178 4230 11190 4263 11157 4247 11134
TIME...MOT...LOC 2104Z 228DEG 36KT 4229 11174 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

McKaughan
2 follow-up statements
015 
WWUS55 KPIH 212121
SVSPIH

Severe Weather Statement
National Weather Service Pocatello ID
321 PM MDT Sat Aug 21 2021

IDC005-212130-
/O.CAN.KPIH.SV.W.0015.000000T0000Z-210821T2145Z/
Bannock ID-
321 PM MDT Sat Aug 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BANNOCK COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4227 11166 4237 11173 4258 11152 4247 11134
TIME...MOT...LOC 2120Z 233DEG 32KT 4239 11158 

$$

IDC007-029-041-212145-
/O.CON.KPIH.SV.W.0015.000000T0000Z-210821T2145Z/
Caribou ID-Franklin ID-Bear Lake ID-
321 PM MDT Sat Aug 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM MDT
FOR SOUTH CENTRAL CARIBOU...NORTHEASTERN FRANKLIN AND NORTHWESTERN
BEAR LAKE COUNTIES...

At 320 PM MDT, a severe thunderstorm was located 7 miles east of
Thatcher, or 14 miles west of Montpelier, moving northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Georgetown and Emmigrant Summit. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4227 11166 4237 11173 4258 11152 4247 11134
TIME...MOT...LOC 2120Z 233DEG 32KT 4239 11158 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

McKaughan
712 
WWUS55 KPIH 212134
SVSPIH

Severe Weather Statement
National Weather Service Pocatello ID
334 PM MDT Sat Aug 21 2021

IDC007-029-041-212140-
/O.CAN.KPIH.SV.W.0015.000000T0000Z-210821T2145Z/
Caribou ID-Franklin ID-Bear Lake ID-
334 PM MDT Sat Aug 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL CARIBOU...
NORTHEASTERN FRANKLIN AND NORTHWESTERN BEAR LAKE COUNTIES IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.

LAT...LON 4227 11166 4237 11173 4258 11152 4247 11134
TIME...MOT...LOC 2128Z 228DEG 36KT 4246 11147 

$$

McKaughan

The office that day

Everything else NWS Pocatello, ID issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 12:46 PM MDTSpecial Weather StatementPIHBear Lake89 min
Aug 21, 2:30 PM MDTSpecial Weather StatementPIHFranklin45 min
Aug 21, 3:10 PM MDTSpecial Weather StatementPIHCuster95 min
Aug 21, 3:28 PM MDTSpecial Weather StatementPIHOneida32 min
Aug 21, 4:11 PM MDTSpecial Weather StatementPIHFranklin34 min
Aug 21, 4:23 PM MDTSpecial Weather StatementPIHCuster97 min
Aug 21, 4:51 PM MDTSpecial Weather StatementPIHCuster24 min
Aug 21, 4:52 PM MDTSpecial Weather StatementPIHCaribou38 min

Nearby

Severe Thunderstorm Warnings in Idaho, 2021Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.